No, it was tracking my path and correctly displaying the waypoints in the correct order when I observed this behavior.

Was this in conjunction with it not noticing that you passed a waypoint due to the GPS coordinates being off from the waypoint coordinates? If so, it will count upwards as it assumes you have to go through that "missed" waypoint. As you continue on down the path, you are getting further from that "missed" waypoint, so your total route distance would increase.

If not, then I'm out of ideas..